package com.clas.liu.myapplication.view.widget;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Shader;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.support.annotation.Nullable;
import android.support.v7.widget.AppCompatImageView;
import android.util.AttributeSet;

/**
 * 功能描述：一个简洁而高效的圆形ImageView
 *

 */
public class CircleImageView extends AppCompatImageView {
    private float width;
    private float height;
    private float radius;
    private Paint paint;
    private Matrix matrix;
    private Bitmap bm;

    public CircleImageView(Context context) {
        this(context, null);
    }

    public CircleImageView(Context context, @Nullable AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public CircleImageView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        paint = new Paint();
        paint.setAntiAlias(true);   //设置抗锯齿
        matrix = new Matrix();      //初始化缩放矩阵
    }

    /**
     * 测量控件的宽高，并获取其内切圆的半径
     */
    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        width = getMeasuredWidth();
        height = getMeasuredHeight();
        float size = Math.min(width,height);
        radius = size / 2;
        setMeasuredDimension((int)size,(int)size);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        Drawable drawable = getDrawable();
        if (drawable == null) {
            super.onDraw(canvas);
            return;
        }
        if (drawable instanceof BitmapDrawable) {
            paint.setShader(initBitmapShader((BitmapDrawable) drawable));//将着色器设置给画笔
            canvas.drawCircle(radius, radius, radius, paint);//使用画笔在画布上画圆
            return;
        }
        super.onDraw(canvas);
    }

    /**
     * 获取ImageView中资源图片的Bitmap，利用Bitmap初始化图片着色器,通过缩放矩阵将原资源图片缩放到铺满整个绘制区域，避免边界填充
     */
    private BitmapShader initBitmapShader(BitmapDrawable drawable) {
        Bitmap bitmap = drawable.getBitmap();
        if(bitmap == null)
            bitmap = bm;
        BitmapShader bitmapShader = new BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
        float scale = (radius * 2.0f) / Math.min(bitmap.getHeight(), bitmap.getWidth());
        matrix.setScale(scale, scale);//将图片宽高等比例缩放，避免拉伸
        bitmapShader.setLocalMatrix(matrix);
        return bitmapShader;
    }

    @Override
    public void setImageBitmap(Bitmap bm) {
        super.setImageBitmap(bm);
        this.bm = bm;
    }
}
